Abstract: This is the first of three reports in which the authors develop design aids and tools for estimating: 1) the effect of pile deformation on the response of bridge piers; and 2) assessing the interplay between soil, pile and pier in the seismic response of a number of different bridge types under varying soil conditions and input ground motions. The report presents a complete set of parametric results in the form of graphs and tables for the seismic response of bridge bents supported either on a single drilled pile or on a 4x5 pile group embedded in three actual layered soil deposits. The input excitation, in the form of vertically propagating S waves, is described through real and artificial accelerograms. Both kinematic and inertial interaction are taken into account; and results are in both the time and frequency domains. The authors present accelerations and displacements for the bridge and pile cap, as well as for internal forces along the piles. They investigate potential errors that may arise when one ignores: 1) radiation damping produced by piles and elastic bedrock; 2) pile cap rotations; 3) the cross-swaying and rocking component of pile foundation response. The results presented in this report are strictly applicable to linear soils and structures.